1. Field of the Invention
This invention relates to a press apparatus for cementing two planar members (for example, glass plates for liquid crystal) together efficiently and highly accurately.
2. Description of the Prior Art
Products using liquid crystal cells have already been established as the parts of optical instruments, electronic instruments, timepieces, etc. However, the usage thereof has been widened more and more. For example, as can be seen from the fact that liquid crystal televisions, large dot displays, display systems for automobiles, thermometers, etc. have been developed one after another, products using liquid crystal have been produced over a very wide field. To produce such liquid crystal cells, the following steps must be completed: the steps of "glass washing, pattern deposition by evaporation, resist printing, exposure, etching, oriented film coating, stripping, rubbing treatment, application of adhesive agent, etc." Now, there is the most important treatment in the step of positioning the alignment marks of two glass plates completely subjected to the above-mentioned steps and cementing the glass plates together. Since the cementing accuracy or the operator's efficiency at this time is generally related directly to the reliability and productivity of finished liquid crystal cells, how accurately and efficiently the glass plates can be cemented together is a great point to manufacturers of liquid crystal.
Here, a liquid crystal cementing apparatus according to the prior art will be described with reference to FIG. 1 of the accompanying drawings.
First, at the initial set position, an upper glass plate is adsorbed to a glass adsorbing movable plate 1 so that the surface of the upper glass plate which is to be cemented faces downward. Also, a lower glass plate is adsorbed to the glass adsorbing movable plate 1 in a predetermined spaced apart relationship with the upper glass plate so that the surface of the lower glass plate which is to be cemented faces upward. Then, the glass adsorbing movable plate 1 is rectilinearly moved manually so that the upper glass plate thereon lies just beneath an upper glass adsorbing plate 2. Next, when the central portion of the upper glass adsorbing plate 2 suspended by four posts 5 and a spring 6 from an alignment base plate 9 placed on a ball receiver 8 supported by a bed 3 is pressed by a lever bar 4, the upper glass adsorbing plate 2 comes into contact with the upper glass plate adsorbed to the glass adsorbing movable plate 1.
The upper glass adsorbing plate 2 starts adsorption, while the adsorption of the glass adsorbing movable plate 1 is released, whereby the upper glass plate is shifted from the glass adsorbing movable plate 1 to the upper glass adsorbing plate 2.
Subsequently, the glass adsorbing movable plate 1 is rectilinearly moved so that the lower glass plate adsorbed thereto lies just beneath the upper glass adsorbing plate 2, and is fixed by a positioning pin 7.
Thus, the upper and lower glass plates become opposed to each other, and alignment marks provided on the upper and lower glass plates are observed by means of two observation devices 10. That is, the deviation between the upper and lower alignment marks is visually observed by means of the observation devices 10, and the alignment base plate 9 is operated by means of two manipulators connected to the alignment base plate 9, thereby modifying the deviation between the upper and lower alignment marks. After the alignment marks have become coincident with each other, the lever bar 4 is again pressed manually to thereby effect the cementing of the upper and lower glass plates.
However, such apparatus according to the prior art has a disadvantage that much time is required before the upper and lower glass plates are set at the press position. Moreover, all the operation is effected manually and the operator directly handles the glass plates, and this leads to a disadvantage that stains such as dust and fingerprints or damages are liable to be imparted to the glass plates. Also, depending on the ability of the operator, the accuracy of alignment or the press pressure during the cementing is not stable and the working efficiency is remarkably irregular, and this means a disadvantage in respect of productivity.